The present invention is an improvement derived from a review of current electronically controlled medical devices, such as parenteral and enteral feeding pumps, and consumer household appliances, such as microwave ovens. These devices typically have touch panel overlays which activate membrane switches. It was found that operators, even those familiar with the device, are sometimes confused with respect to the sequential operation of the device. For example, if one wants to enter a numerical value, in which sequence does one depress: the control mode button, the numerical keypad, and the save/store button? It may also be difficult to determine which operating mode is currently activated. A further problem with overlay control panels is their susceptibility to accidental activation, and manipulation by unauthorized persons.
Rotational dials, such as those found on washing machines, are much easier than overlay control panels to understand and provide positive positional information. However, they present physical limitations. Dials typically protrude from the surface of the device, thus allowing for accidental or unauthorized turning. This is a particular problem for ambulatory devices, such as feeding pumps. The dial also creates a bulkier device. This is even a problem with recessed dials, which in turn, necessitate a larger device housing to accomodate the dial indentation.
Accordingly, it is the objective of the present invention to provide a control device which is easy to understand, prevents accidental and/or unauthorized tampering, and yet avoids protruding dials or major cavities into the device housing.
Briefly, the preferred embodiment of the invention features a disk-shaped handle with a diametrical pivot, permitting pivoting of the handle from a first orientation flush with the surface of the controlled device to a second position perpendicular to the surface of the controlled device. In the second position, rotation of the handle carries with it a generally hemispherical housing in which the hinge or pivot is mounted. The housing, in turn, is mounted for rotation about an axis perpendicular to the surface of the controlled device, and is connected to a rotary switch which may be mounted on a printed circuit board fixed inside the controlled device.
This invention has a number of advantages. It provides rotational dial simplicity without a fixed protruding dial handle, or a large cavity into the device. The operator is forced into an operational sequence by the dial rotation, and the dial position always indicates the activated control mode. Dials are familiar and comfortable control mechanisms.
The addition of the pivoting handle provides a large grip surface without creating a similar sized indentation into the device housing, which would enlarge the overall size of the device. The elimination of the fixed, protruding dial handle provides a more compact device and one which is more suitable for discreet, comfortable ambulatory positioning, such as in a vest or pouch. Further, the handle is preferably a rounded disk, such that there are no sharp edges which might snag and injure the fragile skin of a child, or of an elderly or malnourished patient. The handle in the closed position also avoids fluid spills into the housing cavity. The rounded disk edge tends to slide over, rather than snag on, the patient's skin or clothing.
The use of the pivoting handle also avoids accidental activation of the device, as is possible with a touch panel or a protruding dial. Someone may inadvertantly bump against a stationary panel; also a touch panel may be depressed, or a dial turned, in the normal course of carrying a device in an ambulatory mode. The closed position of the present invention prevents these problems, and also, discourages unauthorized tampering. Accidental or unauthorized manipulation of the controls may be highly undesirable; for example, control changes on a medical feeding pump could result in one of the following conditions which may result in serious patient complications: 1) cessation of fluid delivery, 2) over-or-under delivery, and 3) loss of vital microprocessor-stored information concerning delivery statistics.